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Sonchus oleraceus (L.) L. (sow thistle) is an underutilised functional leafy vegetable with both high nutritional and pharmacological values. In the current study, high performance liquid chromatography ion trap time-of flight mass spectrometry (HPLC-IT-Tof-MS)-based metabolomics in combination with principal component analysis (PCA) were used to provide an overall phytochemical composition of different tissues (leaf, stem and roots) of this underutilised plant. A total of 32 phytochemicals, comprising hydroxycinnamic acids, flavonoids and terpene classes were identified across the three different tissues of S. oleraceus. The study used the new approach of colour coded PCA models to info-graphically depict the metabolic profiles across different parts of the plant. The results of the current study indicate S. oleraceus as a potential source of metabolites with highly claimed nutraceutical properties. As such, the results herein can be used as a template reference for further biological studies aimed at the evaluation of nutraceutical properties of the S. oleraceus plant.

Recent confirmations of glyphosate-resistant Russian thistle (Salsola tragus L.) in Montana, Washington, and Oregon, warrant greater surveillance of herbicide-resistant Russian thistle in western Canada. A randomized-stratified survey of 315 sites in Manitoba was conducted in 2018 to determine the incidence of herbicide resistance in Russian thistle and other weeds sampled post-harvest. Russian thistle populations were collected from 14 of the 315 sites surveyed. None of these populations exhibited resistance to acetolactate synthase inhibitors (tribenuron/thifensulfuron), synthetic auxins (2,4-D ester or fluroxypyr), or glyphosate. This Manitoba survey of herbicide-resistant Russian thistle serves as a baseline for future surveillance efforts.

PREMISE Plants experiencing steep reproductive losses from herbivores should favor strategies promoting tolerance or resistance to that herbivory. However, the degree to which such strategies succeed in improving plant fitness under natural conditions needs further evaluation, especially for iterocarpic species. We tested whether reproductive effort by the iterocarpic Cirsium undulatum Spreng. (Wavyleaf thistle) provided within-season tolerance for floral herbivory through response to apical damage. METHODS We imposed apical damage and manipulated floral herbivory on later-flowering, non-apical flowerheads for two seasons. We asked: (1) is there evidence of compensatory potential to tolerate apical flowerhead damage? If so, (2) does the amount of herbivore pressure on non-apical flowerheads influence the magnitude of any compensatory response; and (3) is the response to apical damage sufficient to increase plant seed production under ambient floral herbivory over the flowering season? RESULTS Plants showed compensatory potential for apical head loss; apical damage increased seed contributions from later, lower positioned flowerheads. Further, the intensity of subsequent herbivore pressure influenced compensation outcomes. Equitable seed production under both levels of ambient herbivory occurred only in the year in which plants were larger and insect pressure was lower. Finally, the response to apical damage was sufficient to compensate for apical seed loss, but it did not consistently increase overall annual seed production under ambient floral herbivory. CONCLUSIONS Although this iterocarpic species can compensate for apical damage, tolerance for floral herbivory varied between years.

The present study was carried out to assess the underlying physiological and biochemical events of salinity adaptation in blessed thistle (Silybum marianum Gaertn.) and peppermint (Mentha haplocalyx Briq.). The seedlings of both species were exposed to four different salt (NaCl) concentrations: 30 mM (3.8 mS cm–1), 60 mM (7 mS cm–1), 120 mM (13.4 mS cm–1), and 180 mM (19.6 mS cm–1), and the changes in biomass, osmoprotectant accumulation, ion concentrations, and antioxidant enzymes activity were recorded every 15 days in blessed thistle and every 10 days in peppermint for three samplings. The results showed that salinity significantly increased malondialdehyde (MDA) and proline accumulation in leaves and roots (3- to fourfold) but had little effect on the chlorophyll content of leaves at the first sampling in both species. The soluble protein content of blessed thistle significantly increased after salt treatment at the first sampling (83% in roots and 55% in the aerial parts of plants), whereas peppermint was less affected. K+/Na+ and Ca2+/Na+ ratios in both species exposed to 180 mM NaCl were more than tenfold lower than the untreated control at all three samplings. Superoxide dismutase (SOD) and catalase (CAT) activity were significantly affected by salinity in blessed thistle but not in peppermint, while peroxidase (POD) activity increased with increasing salinity in peppermint but not in blessed thistle at all three samplings. These results suggested blessed thistle and peppermint utilized different tolerance strategies which shedding new light on how to grow halophytes in saline lands.

Chemical weed control method caused environmental hazards and residual effects in crops and soil. Alternate approach to control weeds is getting attentions in sustainable production system. Use of aqueous extracts of weed is getting scientific attention as eco-friendly alternative to chemical herbicides especially under scenario of fast increasing herbicide resistance in weeds. To investigate the herbicidal potential of aqueous extract of winter weed of Sonchus oleraceus L. (Sow thistle) on summer weed Oryza punctate L. (red rice) seed emergence and initial seedling growth, a study was planned. In this study, seeds of O. punctate were incubated in seven concentrations (0, 0.25, 0.50, 1, 2, 4, and 8%) of different parts i.e. leaves, stem, flower of S. oleraceus. All the tested concentrations of various plant parts of S. oleraceus significantly inhibited the mean emergence time, emergence index, emergence percentage (%), time taken to 50% emergence as well as growth of O. punctata weed. However, maximum mean emergence time (5.26 days), minimum germination index (1.69), germination percentage (40%), root length (2.04 cm), shoot length (5.71 cm), fresh weight (59 g), dry weight (4.06 g) was noted at 8% concentration with fruit aqueous extract of S. oleraceus. Seed of O. punctata take maximum time to complete 50% emergence (3.33 days) under control where we applied distilled water. Results suggested fruit extract of S. oleraceus at 8% concentration can be used potential bio-herbicide for the control of O. punctate. Key words: Chemical, eco-friendly, herbicidal potential, fruit extract

Centaurea benedicta L. is an annual herbaceous plant which belongs to the Asteraceae family. It is native to the Mediterranean region and western Asia and is commonly known as blessed thistle, holy thistle, St Benedict’s thistle or spotted thistle. Traditionally, it has been used to treat bubonic plague and possesses diuretic, galactagogue, liver-strengthening and wound healing properties. Recent research studies have investigated its anticancer, antiinflammatory, antioxidant and other therapeutic properties. Several studies have also reported its antimicrobial activity against a range of bacterial pathogens. However, most of these studies were preliminary and only tested relatively high concentrations of the extracts. Additionally, most studies screened a limited number of pathogens. Cnicin is the main chemical compound present in C. benedicta and it has been widely investigated. However, few other compounds from this plant have been identified and/or investigated, and further phytochemical studies are warranted. Interestingly, pure cnicin has good anticancer activity, whilst the crude extracts lack cytotoxic properties. Phytochemical analyses of C. benedicta extracts reveal the presence of multiple flavonoids, tannins, terpenoids and lactones, although few specific phytochemicals within these phytochemical classes have been identified. A limited number of research studies have determined the toxicity profile of C. benedicta in order to evaluate its safety for human use. Substantially more detailed studies are required to rigorously investigate the therapeutic properties and phytochemistry of C. benedicta, which may ultimately lead to the development of new plant-based therapeutic medicines.

The fate of the enigmatic species Carduncellus matritensis looked clear when the type locality in Cerro Negro was razed by the growing of Madrid at the beginning of the XX century: it was officially listed as one of the six extinct species in the Red Book of the Spanish flora. The controversy on the identity of the taxon continued on the basis of the scarce and undeveloped samples gathered before the purported extinction and the species was not accepted by some specialists in the genus. One year ago, some relictic populations of an unknown species of Carduncellus were located in the surroundings of the Gran Madrid, 50 km south of the type locality. After careful review of the available materials and new gatherings, we conclude that Carduncellus matritensis did escape extinction and can be found on the same expansive clay soils that characterize the Cerro Negro. On morphological basis, we also conclude that it is a distinct species that cannot be reduced to any of the extant species of the genus., INTRODUCTION SYSTEMATIC TREATMENT LITERATURE CITED

A study to determine the volatile fraction of distillates with added 50% and 70% ethanol extracts of donkey thistle (Onopordum acanthium L.) was conducted. The extracts were added to the pure distillate from the grapes of Melnik-55 grapevine variety in amounts of 20, 50, 80, 100, 200, 400 and 600 ml. The remaining amount to liter was a pure distillate. A distillate of Melnik-55 grapes (without extracts) was used as a control. The addition of 50% ethanol extract of Onopordum acanthium L. increased the total volatile composition of variants 1000:20 and 1000:50, in comparison to the control sample. Higher levels of esters and higher alcohols were found in the same variants. Incorporation of the 50% and 70% ethanol extracts of donkey thistle resulted in increased final total terpene content of the distillates. By increasing the amount of the added 50% ethanol extract, a reduction in the concentrations of acetaldehyde and ethyl acetate was found in the distillates. The basic ester in all the distillates analyzed was ethyl acetate, and the major higher alcohols were 2-methyl-1-butanol, 3-methyl-1-butanol, 1-propanol and 2-butanol. By applying of 50% and 70% ethanol extracts of the plant, a reduction in methanol content in the final distillates was observed. A prospect was the application of 50% ethanol extracts of Onopordum acanthium L, especially variants 1000:20 and 1000:50. This two variants showed higher final levels of aromatic compounds (beverage quality) and slightly higher final levels of terpenes (biological value) compared to the control. The other variants of this group had proven lower levels of methanol (improved toxicological quality) compared to the control., Проведено е изследване за определяне на летливата фракция на дестилат с добавени 50% и 70% етанолни екстракти на магарешки бодил (Onopordum acanthinum L.). Екстрактите са добавени в чист дестилат от грозде на сорта Мелник-55 в количества 20, 50, 80, 100, 200, 400 и 600 ml. Останалото количество до литър е дестилат. Като контрола служи чистия дестилат (без екстракти) на грозде от сорта Мелник-55. Установено е, че добавянето на 50% етанолен екстракт на Onopordum acanthinum L. повишава общия летлив състав на варианти 1000:20 и 1000:50, значително над установеното в контролата. Прилагането на 50% и 70% етанолни екстракти на магарешки бодил води до повишаване на финалното общо терпеново съдържание на дестилатите. С увеличаване количеството на добавен 50% етанолен екстракт е установено редуциране в концентрациите на ацеталдехид и етилацетат в дестилатите. Основен естер във всички анализирани дестилати е етилацетат, а основни висши алкохоли са 2-метил-1-бутанол, 3-метил-1-бутанол, 1-пропанол и 2-бутанол. При прилагане на 50% и 70% етанолни екстракти на растението, се констатира редуциране на метанолното съдържание в дестилатите. Перспектива представлява прилагането на 50% етанолни екстракти на Onopordum acanthium L, особено варианти 1000:20 и 1000:50. В тези два варианта се установяват високи крайни нива на ароматичн съединения (качество на напитката) и малко по-високи крайни нива на терпени (биологична стойност), в сравнение с контролата. Останалите варианти на тази група са с доказани по-ниски нива на метанол (подобрено токсикологично качество), в сравнение с контролата.

The biotic resistance hypothesis asserts that native species may hinder the invasion of exotic species, which can occur either directly or indirectly by influencing interactions between exotic and local species. Aphid-tending ants may play a key role in the indirect biotic resistance to plant invasion. Ants may protect aphids, thus increasing their negative effect on exotic plants, but may also deter chewing herbivores, thus benefiting exotic plants. We studied native aphid-tending ants (Dorymyrmex tener, Camponotus distinguendus, and Dorymyrmex richteri) on exotic nodding thistles (Carduus thoermeri), which are attacked by thistle aphids (Brachycaudus cardui) and thistle-head weevils (Rhinocyllus conicus). We evaluated the impact of ants, aphids, and weevils on thistle seed set. We compared ant species aggressiveness towards aphid predators and weevils and performed ant-exclusion experiments to determine the effects of ants on aphid predators and weevils. We analysed whether ant species affected thistle seed set through their effects on aphids and/or weevils. The ant D. tener showed the most aggressive behaviour towards aphid predators and weevils. Further, D. tener successfully removed aphid predators from thistles but did not affect weevils. Excluding D. tener from thistles increased seed set. Analyses supported a negative indirect pathway between the aggressive D. tener and thistle seed set through aphid populations, while the other ant species showed no indirect effects on thistle reproduction. Therefore, aggressive aphid-tending ants may enhance biotic resistance by increasing aphid infestation on exotic invasive plants. This study highlights the importance of indirect biotic resistance in modulating the success of invasive species.

One of the main obstacles of classical biological control is that biological control organisms cannot be recalled once they are released in nature. It is particularly true for the flowerhead weevil, Rhinocyllus conicus Frolich, which was released as a biological control organism for the invasive musk thistle, Carduus nutans L. (MT). While weevils successfully suppressed introduced populations of musk thistles and other invasive thistle species, non-target attacks have been reported on multiple native thistles including federally listed threatened and endangered (T&E) thistle species. To investigate the foraging behavior of female weevils on invasive and native thistles, we examined volatile organic compounds (VOCs) emitted from MT and a T&E plant species, Sacramento Mountains thistle, Cirsium vinaceum Wooton & Standley (SMT) in the Lincoln National Forest, New Mexico. We used a dynamic headspace volatile collection system and gas chromatography-mass spectrometry to compare volatile profiles between MT and SMT. Female weevils reacted to 7 electrophysiologically active chemical compounds in the blends based on gas chromatography-electroantennography. The behavioral response of female weevils was indifferent when VOCs from both thistles were offered in y-tube olfactometry experiments. Yet, they preferred VOCs collected from MT to purified air. The searching time of female weevils was longer to VOCs collected from SMT over controls. Investigating signals during the initial host recognition of released biological control organisms may open new opportunities to reduce non-target attacks on T&E plant species.

Soft chemical treatments of dried stalks of the spotted golden thistle yielded novel sorbents; both the stiff nature and mass of the raw material were preserved. For minimal environment impact, the...

The benefits of no-till fallow, which include reduced soil erosion, improved soil health, and increased stored soil water, are in jeopardy because of the widespread development of glyphosate resistance in Russian thistle. The objective of this research was to evaluate the efficacy of soil-active, residual herbicides for Russian thistle control in no-till fallow. The combinations of sulfentrazone + carfentrazone and flumioxazin + pyroxasulfone, and metribuzin alone were each applied in late fall, late winter, and split-applied in late fall and late winter at three sites: Adams, OR, in 2017–2018; Lind, WA, in 2018–2019; and Ralston, WA, in 2019–2020. All treatments provided good to excellent control of the initial flush of Russian thistle when assessed in mid-May, except the late-fall application of metribuzin at all three sites, and the late-fall application of sulfentrazone + carfentrazone at Adams. Cumulative Russian thistle densities, evaluated monthly throughout the fallow season, were lowest for the sulfentrazone + carfentrazone treatments, except for the late-fall application at Adams. However, flumioxazin + pyroxasulfone and metribuzin provided greater control of tumble mustard and prickly lettuce than did sulfentrazone + carfentazone. Sulfentrazone + carfentrazone, flumioxazin + pyroxasulfone, and metribuzin can all be used for Russian thistle control in fallow. To reduce the risk for crop injury to subsequently planted winter wheat, a late-fall application of sulfentrazone + carfentrazone may be the preferred treatment in low-rainfall regions where winter wheat–fallow is commonly practiced. A late-winter application may be preferred in higher rainfall regions where a 3-year rotation (e.g., winter wheat–spring wheat–fallow) is common. Flumioxazin + pyroxasulfone should be considered if other broadleaf weeds, such as tumble mustard or prickly lettuce, are of concern. The use of these soil-applied herbicides will reduce the need for the frequent application of glyphosate for Russian thistle control in no-till fallow.

Cryopreservation is a valuable tool that could potentially create an alternate plant preservation strategy for species at risk such as Hill’s thistle. The present study is focused on a successful paradigm involving conservation, propagation and redistribution (CPR), emaphasizing the usefulness of cryopreservation techniques for plant conservation using Hill’s thistle (Cirsium hillii. (Canby) Fernald). A cryopreservation protocol was established using the droplet-vitrification method for 5-week-old shoot tips of in vitro grown cultures. More than 90% of shoot tips showed regrowth and nearly all regenerated plants were able to survive in the greenhouse. The survival, growth, and development of plants from cryopreserved shoot buds and their performance in field conditions were all comparable or better than the plants from non-cryopreserved buds. Reintroduced plants flowered following overwintering and the magnitude of flowering was site dependent with ca. 80% flowering observed in one site. The site dependent flowering patterns were assessed using phytohormone profiling and compared to herbivory, a common biotic stressor of these plants. Lower tryptophan concentrations led to higher flowering except in alvars, where the limestone resisted root penetration resulting in poor flowering. The presence of tryptamine in the greenhouse acclimatized or alvar field leaves suggested the preparedness of the plants for herbivory/grazing. Serotonin and melatonin concentrations were lower in flowering plants and in sites where the biotic/abiotic stress was minimal. This study provides evidence of the effectiveness of the CPR model in species recovery programs for endangered species. Physiological characterization of plants developed from cryopreserved tissues can be useful for fundamental and applied research in stress adaptation and reproductive biology of plants. Cryopreservation is an asset for conserving, preserving and redistributing plant species at risk. Flowering patterns in cryopreserved plants may be modulated by site characteristics and indoleamines play a role in flowering responses.

The purpose of the study is to conduct an objective analysis of the effectiveness of technological methods to control the development of pink and gray thistle among industrial plantations of grapes, taking into account their features and modern control measures. Accounts for the number and development of weeds, conducted at the end of the growth phase of grape shoots, in areas where the soil was kept in a state of black steam showed that the prevalence of pink and gray thistle plants in various biological and coenotic groups reached 53.1–57,4 % with an average number of 3.4–3.7 pieces/m2, which developed along the axis of a number of bushes and a protective strip. Growing in between rows of grapes of intermediate crops, winter rye and sorrel, causes qualitative and quantitative changes in the formation of species composition, number and development of weeds, including perennials – thistle pink and gray. In the sectors between rows, free from intermediate crops, along the axis of a number of bushes and protective strip, the development of pink and gray thistles does not differ significantly from similar processes in the area, which was kept constantly in a state of black steam. It is established that traditional control methods are ineffective because they do not provide complete removal of weeds, require large expenditures of material and financial resources. The most promising for reducing costs and achieving maximum efficiency in the control of pink thistle is the integrated application of agronomic, phytocenological and chemical measures, with due regard for the biological characteristics of weed development. Key words: segetal vegetation, weeds, herbicides, analysis of efficiency of technological receptions, winter rye, sorrel sour, receptions of cultivation of plantings, thistle pink, thistle gray.

The leaf-feeding beetle, Cassida rubiginosa, is an oligophagous biocontrol agent capable of feeding on most species in the tribe Cardueae (thistles and knapweeds). The beetle was released in New Zealand in 2007, primarily to control Cirsium arvense (Californian thistle), with the recognition that it had potential to control multiple thistle weeds. The objective of this study was to test the impact of different densities of Cassida rubiginosa larvae (0, 50, 100, or 200 per plant) on the growth and reproductive performance of the annual thistle weed, Carduus pycnocephalus (slender winged thistle). Since the effectiveness of biocontrol agents is often enhanced when plants are stressed, different levels of growth constraint were imposed by growing the weed in different pot sizes (0.5, 1, 5, and 12 litres). We hypothesised that feeding damage by Cassida rubiginosa larvae would have a greater impact on the weed when grown in smaller pots, since root growth would be constrained, and the weed’s ability to compensate for feeding damage would be restricted. Contrary to our hypothesis, pot size had no effect on feeding damage by Cassida rubiginosa on Carduus pycnocephalus. As expected, most measures of plant performance increased with larger pot sizes, including plant height, biomass, and the number of seedheads per plant. The results of this study indicate that Cassida rubiginosa is unlikely to contribute to the control of Carduus pycnocephalus. Additional oligophagous biocontrol agents targeting the rosette stage and seed production should be considered for release in New Zealand.

Variegated thistle in East Coast North Island hill country reduces pasture and livestock productivity. To quantify the impact of increasing amounts of pasture cover (herbage mass) on this weed, variegated thistle seeds were hand-sown in autumn into pasture swards that ranged in height from 0 cm (bare ground) to 12 cm, on an East Coast property near Gisborne. Sward height was maintained by mowing without damaging the thistle plants. Increasing pasture cover reduced thistle emergence, height, diameter, biomass, survival, and seed production. By early June, 7 weeks after sowing, thistle emergence was greatest from bare ground and from maintaining a pasture at a height of 3 cm (>1100 kg DM ha-1 in autumn) and declined with increasing pasture height. By December, thistle height, diameter, biomass, flowerhead production and survival were highest in the bare ground treatment (thistle biomass ≈760 g plant-1), much lower in the 3-cm pasture height treatment (≈20 g plant-1), negligible in the 6-cm (>1600 kg DM/ha) and nil in the 8-cm (>1800 kg DM ha-1) and 12-cm (>2700 kg DM ha-1) pasture treatments (P

To identify appropriate genotypes for breeding varieties suitable for semi-arid areas, yield components, as well as morphophonological traits of 127 safflower genotypes, were assessed at the Seed and Plant Improvement Institute, Iran. Cluster analysis revealed four distinct groups. The largest group (third cluster) includes 48 genotypes with characteristics such as mostly yellow-coloured flowers, mostly thorny with few thistle genotypes, relatively early-flowering, relatively high number of heads and grains per plant, highest 1000-grain weight with the highest grain yields. In contrast, the smallest group (second cluster) contains 13 genotypes with characteristics such as yellow florets, semi-dwarf, thorny, moderately late-flowering, low number of heads per plant and number of grains per head, low 1000-grain weight, and low grain yield. Principal component analysis results showed that the three components accounted for 29.5, 15.9 and 11.1% of the total variation, respectively. Graphic representation of the biplots based on the first and second principal components showed that the experimental genotypes were classified into four groups. The results also indicated that stem diameter, the number of branches, heads per plant and grains per head had the highest correlation with the first component, and grain yield, flower colour, flowering initiation and plant height had the highest correlation with the second component. These traits can be considered as an appropriate index for the selection of elite safflower genotypes for breeding varieties suited to cultivation in semi-arid conditions.

It is analyzed that the formation of pathogenic microbiome cultural plant is due to the interaction of populations of phytopathogenic micromycetes with plants of the variety as a biotic ecological factor in the formation of phytopathogenic background in agrophytocenoses of varieties cultural plant. The seeds of such promising varieties of cultural plant as soybeans (Kent and Suzirya), buckwheat (Son and Sophia), thistle (Riches) and yellow mustard (Forge) for micromycetes were analyzed. We carried out the analysis of seeds types of such cultural plant as soybean, buckwheat, thistle, mustard yellow on the location micromycetes and identified phytopathogenic fungi: Alternaria alternate Fr., Fusarium oxysporum Schleht, Cladosporium herbarum Lket Gray, Botrytis cinerea Pers. ex Fr., Ascochyta fagopyri Bres., Alternaria tenuissima (Kunze) Wiltshire, Aspergillus P. Micheliex Haller, Penicillium Link., Mucor Micheliex F. It was determined that the species composition of phytopathogenic micromycetes in soybean and thistle seeds s is much more diverse compared with buckwheat and mustard yellow seeds. Among the identified micromycetes there are species with varying degrees of parasitism: obligate and facultative saprotrophs and parasites. To assess the typicality of the species and determine its position in the structure of dominance in the agrocenosis of cultivated plants, the criterion of the frequency of occurrence of the species was used. Fungi of genera Alternaria alternate, Fusarium oxysporumare characterized by different frequency of occurrence (11–30%). The seeds of Suzirya soybean variety and Son and Sophia buckwheat varieties are intensively inhabited by fungi of the genus Penicillium (60–90%). We determined the indicator of similarity species composition of micromycetes withdrawn from seeds types of cultural plants by Jacquard similarity coefficient. It is established that seeds of soybeans and thistle as well as the seeds of thistle and yellow mustard are characterized with high level of micromycetes similarity (indicator of similarity — 75 and 66.7% respectively). At the same time, seeds of buckwheat and thistle as well as buckwheat and mustard yellow were characterized with low level of micromycetes similarity – 12.5 and 22.2%, respectively. The analyzed indicators provide an opportunity to evaluate seeds types of cultural plant in order to avoid ecological risks and biological pollution of agrocoenoses during sowing and cultivation of crops of different varieties.

Premise of research. Population connectivity, the exchange of genes among geographically separated subpopulations, is thought to be a key process for the maintenance of genetic diversity and the su...

Whether plant populations are limited by seed or microsite availability is a long-standing debate. However, since both can be important, increasing emphasis is placed on disentangling their relative importance and how they vary through space and time. Although uncommon, seed addition studies that include multiple levels of seed augmentation, and follow plants through to the adult stage, are critical to achieving this goal. Such data are also vital to understanding when biotic pressures, such as herbivory, influence plant abundance. In this study, we experimentally added seeds of a native thistle, Cirsium canescens, at four augmentation densities to plots at two long-term study sites and quantified densities of seedlings and reproductive adults over 9 years. Recruitment to both seedling and adult stages was strongly seed-limited at both sites; however, the relative strength of seed limitation decreased with plant age. Fitting alternative recruitment functions to our data indicated that post-dispersal mortality factors were important as well. Strong density-dependent mortality limited recruitment at one site, while density-independent limitation predominated at the other. Overall, our experimental seed addition demonstrates that the environment at these sites remains suitable for C. canescens survival to reproduction and that seed availability limits adult densities. The results thus provide support for the hypothesis that seed losses due to the invasive weevil, Rhinocyllus conicus, rather than shifting microsite conditions, are driving C. canescens population declines. Shifts in the importance of density-dependent recruitment limitation between sites highlights that alternate strategies may be necessary to recover plant populations at different locations.

Recently, thorny (Silybum marianum) plants have gained considerable popularity in Ukraine. In addition to the proven medicinal properties of this plant for the prevention of human diseases, the use of milk thistle in other areas is increasing. Milk thistle is used as a vegetable plant because its young leaves have nutritional value. It is also grown as a valuable summer honey plant capable of producing honey at 50–70 kg of honey per hectare.Increasingly, there are reports of the introduction of thistle spotted into the modern crop rotation. However, often the technology of growing it has not yet been studied, so traditional technologies are used, which are adapted to regional conditions for the cultivation of spring early crops of a wide-row sowing method. The control of zinc content, like other toxicants, in vegetative mass and seeds of milk thistle, due to insufficient study of this culture, is very rare. This requires further study of the intensity of zinc accumulation in milk thistle plants with modern cultivation technologies that involve the use of a wide range of mineral fertilizers.Field studies were conducted during 2017–2019 on gray medium loam soil in the farms of Vinnytsia region. Sow thistle spotted in spring time using five fertilizer options: applying nitrogen fertilizer ammonium nitrate, phosphorus fertilizer superphosphate is simple, potassium fertilizer potassium chloride, fertilizer mixtures: ammonium nitrate, superphosphate simple, potassium chloride. Based on the results of laboratory analysis of zinc content in leaf mass and seed thistle spotted, the accumulation coefficient was calculated as the ratio of zinc content in the plant to the content of mobile zinc forms in the soil and the hazard ratio as the ratio of zinc content in the plant to MPC.The intensity of zinc accumulation by the leaf mass and seeds of the milk thistle for feeding it with mineral fertilizers was studied. The accumulation coefficient and the hazard coefficient of zinc in the leaf mass and seeds of the milk thistle for feeding it with ammonium nitrate, potassium chloride, and superphosphate were established. It is proved that with the use of fertilizers less zinc is accumulated by the seeds of milk thistle when using a mixture of ammonium nitrate, simple superphosphate and potassium chloride, and leaf mass — potassium chloride. The highest level of zinc accumulation by leaf mass and silybum seeds was observed when fertilizing crops with ammonium nitrate.When using potassium chloride as a fertilizer, the zinc content in the leaf mass of silybum thistle increased by 14.5%, simple superphosphate — by 15.8%, a mixture of ammonium nitrate, simple superphosphate and potassium chloride — by 42.7%, ammonium nitrate — by 81.6%. The use of a mixture of ammonium nitrate, simple superphosphate and potassium chloride causes an increase in the zinc content in the dry matter of the seeds of milk thistle by 11.8% compared to the version without fertilizing. The introduction of simple superphosphate contributes to an increase in zinc content by 17.2%, potassium chloride — by 23.4%, ammonium nitrate — by 26.9%.